At Sea Testing of the Popeye Fishbox Bycatch Reduction Device Onboard the FV Adelaide Pearl for Approval in Australia’S Northern Prawn Fishery

At sea testing of The Popeye Fishbox bycatch reduction device onboard the FV Adelaide Pearl for approval in Australia’s Northern Prawn Fishery

Erik Raudzens Australian Fisheries Management Authority

Erik Raudzens At sea testing of The Popeye Fishbox bycatch reduction device onboard the FV Adelaide Pearl for approval in Australia’s Northern Prawn Fishery January 2007

AFMA 173 Northbourne Ave Civic ACT 2600

This report should be cited as: Raudzens, E.E. (2007) At sea testing of The Popeye Fishbox bycatch reduction device onboard the FV Adelaide Pearl for approval in Australia’s Northern Prawn Fishery Australian Fisheries Management Authority, Canberra.

This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth available from AusInfo. Requests and inquiries concerning reproduction and rights should be addressed to the Manager, Legislative Service, AusInfo, GPO Box 1920, Canberra ACT 2601.

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Acknowledgements

The author and AFMA are appreciative of the many individuals and groups that provided advice and support for the following trial. Particular mention goes to:

• A. Raptis PTY LTD for their cooperation with the trial. • Mark Robson skipper of the FV Adelaide Pearl • The crew of the Adelaide Pearl (Jackie, Nick, Watto, and Suey) for their patience in separating prawn catch during the trial • Robert ‘Popeye’ Bennett for his council

This project was funded by the National Heritage Trust through the Department of Agriculture Fisheries and Forestry (as part of Project No. 44144-National strategies to address marine wildlife bycatch issues in Australian fisheries).

i Executive Summary

The Popeye Fishbox Bycatch Reduction Device (Popeye Fishbox BRD, hereafter) was assessed for approval in Australia’s Northern Prawn Fishery (NPF) against the NPF Bycatch Subcommittee’s performance requirements during October and November 2006. The assessment was undertaken over three weeks for a total of 82 trawls, with 54 trawls trialed with the BRD positioned at a distance of 70 meshes from the codend draw strings and a further 28 trawls trialed at 100 meshes.

During the assessment twin trawl nets each containing the same standard Turtle Excluder Device (TEDs) were compared. One net contained the Popeye Fishbox BRD while the other net did not contain a BRD. All small bycatch (including sharks and rays) from both nets were separated and weighed in lug baskets. All prawn catch was also weighed separately to assess the effect on prawn catches.

Tests with the BRD located at 70 meshes from the codend draw strings produced a 48% reduction in the weight of small bycatch, an 87% reduction in the number of seasnakes captured and a 35% reduction in the number of sharks and rays captured. Tests with the BRD located at 100 meshes from the codend draw strings produced a 28% reduction in the weight of small bycatch and 27% reduction in the number of sharks and rays captured. Differences in the catch of prawns between nets with and without the BRD were not statistically different.

The Popeye Fishbox BRD has achieved the best results to date for BRDs trialed in the NPF making the implementation of the BRD in the NPF highly desirable. Testing of the BRD at different distances from the codend drawstrings during the trial (70 and 100 meshes) suggests that the location of the Popeye Fishbox BRD (and other BRDs) is an important factor in achieving improved bycatch reduction. Further testing of the BRD would be highly beneficial in defining bycatch reduction performance.

ii Table of Contents

Acknowledgements ...... i

Executive Summary ...... ii

Table of Contents ...... iii

List of Figures...... iv

List of Tables ...... v

Introduction...... 1

Background ...... 1

Methods ...... 2

Results...... 4

BRD located 70 meshes from codend drawstrings...... 4

Shark and rays during the 70 meshes trial...... 9

Seasnakes...... 12

BRD located 100 meshes from codend drawstrings...... 13

Sharks and rays during 100 meshes trial...... 16

Banana prawn catches...... 19

Catch composition...... 20

Discussion...... 23

Conclusions/Recommendations...... 24

References ...... 25

iii List of Figures

Figure 1: Sketch of Popeye’s Fishbox BRD. Source QDPI...... 2

Figure 2 a,b: Position of Popeyes’s Fishbox BRD during the trial. Source QDPI...... 4

Figure 3: Total small bycatch (kg) by each trawl for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 5

Figure 4: Total prawn catch (kg) by each trawl for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 6

Figure 5: Mean total bycatch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 6 Figure 6: Mean total prawn catch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 7

Figure 7: Mean total bycatch (kg + 95% C.I.) for dusk, early night, late night and dawn hauls for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 8

Figure 8: Mean total prawn catch (kg + 95% C.I.) for dusk, early night, late night and dawn hauls for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 8

Figure 9: Total count of all shark species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 10

Figure 10: Total count of all ray species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 10 Figure 11: Total count of all seasnake species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 12

Figure 12: Total small bycatch (kg) by each trawl for nets containing Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF...... 14

Figure 13: Total prawn catch (kg) by each trawl for nets containing Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF...... 14

Figure 14: Mean total bycatch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF...... 15

Figure 15: Mean total prawn catch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF...... 15

Figure 16: Total count of all shark species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 17

Figure 17: Total count of all ray species captured for Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 17

Figure 18: Mean total bycatch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD whilst targeting banana prawns (9-16 Nov 2006)...... 19

Figure 19: Mean total prawn catch (kg + 95% C.I.) for Popeye’s Fishbox and no BRD whilst targeting banana prawns (9-16 Nov 2006)...... 19

iv Figure 20: Proportion of demersal, pelagic and other fish species from nets containing in Popeye’s Fishbox and no BRD obtained from subsamples during the BRD trial (24 Oct-16 Nov 2006) conducted in the NPF...... 20

List of Tables

Table 1: Comparison of Popeye Fishbox bycatch and prawn catch during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 7

Table 2: Three way ANOVA of mean bycatch for Popeye’s Fishbox, No BRD and time of shot (dusk, early night, late night and dawn) during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 8

Table 3: Three way ANOVA of mean prawn catch for Popeye’s Fishbox, No BRD and time of shot (dusk, early night, late night and dawn) during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 9

Table 4: Comparison of shark catches for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 11

Table 5: Comparison of ray catches for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 12

Table 6: Comparison of seasnake catches for nets containing Popeye’s Fishbox and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF...... 13

Table 7: Comparison of Popeye Fishbox bycatch and prawn catch during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF...... 16

Table 8: Comparison of shark catches for nets containing Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF...... 18

Table 9: Comparison of ray catches for nets containing Popeye’s Fishbox and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF...... 18

Table 10: Comparison of Popeye Fishbox bycatch and prawn catch whilst targeting banana prawns during the BRD trial (24 Oct-16 Nov 2006) conducted in the NPF...... 20

Table 11. Counts of small bycatch species/taxa from subsamples of shots 8, 14, 26 and 52 BRD trial (24 Oct-16 Nov 2006) conducted in the NPF. D = Demersal fish taxa; P = Pelagic/semi-pelagic fish taxa, O = Other or unclassifiable fish taxa...... 21

v Introduction

Background The Northern Prawn Fishery (NPF), as a tropical penaeid trawl fishery, is categorised by its high biodiversity and bycatch volume. Over 400 fish species have been recorded in NPF bycatch, as well as 6 species of sea turtles, more than 12 species of seasnakes, over 50 species of sharks and rays and 234 invertebrate species (Stobutzki et al., 2001a & b). Historically, bycatch to catch ratios of prawn catches in subtropical trawl fisheries have been recorded to be in excess of 9 to 1 (e.g. for every 100 kg catch, 90 kg is discarded as bycatch) (Barratt et al., 2001). Such high bycatch volumes have led to prawn trawling being recognised as one of the least selective forms of commercial fishing (Alverson, 1994).

The assessment of bycatch and demonstrating ecologically sustainable practice has been a focus of recent fisheries research and management (e.g. Stobutzki et al., 2001b, 2002, Hall and Mainprize, 2005). In recent years the NPF has become a national leader in addressing bycatch sustainability issues via management arrangements such as its Bycatch Action Plan (BAP) and its strong support for the development and funding of relevant research projects. Recent achievements have included a 99% reduction in turtle catches and the mandatory use of Turtle Excluder Devices (TEDs) and Bycatch Reduction Devices (BRDs) (Brewer et al., 2006).

Despite such successes there has been increasing requirements for Australian fisheries to demonstrate ecologically sustainable development to maintain a high level of acceptance of their practices with national stakeholders and in the global marketplace. The NPF, under the management of the Australian Fisheries Management Authority (AFMA), is required to conform to legislative requirements including the Environmental Protection and Biodiversity Conservation (EPBC) Act 1999, and the Fisheries Management Act 1991. Such legislation requires all Commonwealth fisheries to have management practices in place that address long- term sustainability. In addition, the Federal Minister for Fisheries, Forestry and Conservation, has issued a formal direction to AFMA to take decisive action to ensure the sustainability of our fish stocks and to secure the Australian fishing industry’s future. In response to the Direction and in particular to bycatch issues AFMA has committed to halve bycatch in all Commonwealth fisheries by 2008.

The introduction, and concurrent use, of TEDs and BRDs to reduce bycatch is a relatively new concept in fishing practice with the devices now compulsorily employed in the NPF for just over five years. Consequently there is an ongoing process of development in order to maximise bycatch exclusion and minimise prawn loss (Day, 2000). Whilst legally binding definitions of TEDs and BRDs have been developed and approved by NORMAC (Northern Prawn Fishery Management Advisory Committee), and NPF vessels must use devices that conform to these specifications, NORMAC provided scientific permits to operators wishing to trial new designs. This encourages NPF operators to develop new, innovative and effective TEDs and BRDs (Day, 2000).

In order to gain approval for use, BRDs must meet the NPF Bycatch Subcommittees performance requirements which stipulate that BRDs must achieve a reduction in bycatch of 10% when compared to a net without a BRD over a trial period of two weeks. To date five BRD’s have gained approval in the NPF with reductions in bycatch varying from 10-25%. Previous studies have found the performance of BRDs

1 to be variable with studies suggesting factors such as the location of the BRD and the amount and type of bycatch encountered effecting results. The majority of studies have suggested that locating BRDs closer to the codend drawstrings would improve bycatch reductions.

The Popeye Fishbox BRD was developed by Robert ‘Popeye’ Bennett. Mr Bennett has extensive experience in the NPF both as a commercial fisherman and as a net maker. This BRD has been previously field-trialed in the United States of America and Queensland Prawn Fisheries, by NOAA and QDPI, respectively. Results from the QDPI trial achieved a reduction in bycatch of 30% with insignificant loss of prawn catch whilst the BRD was located at 90 meshes from the codend drawstrings.

The Popeye Fishbox BRD is a rigid framed BRD that has been designed to create a turbulent back-current of water flow with the net (Fig. 1). The creation of a turbulent back-current of water is thought to attract fish seeking to escape the net as they instinctively seek areas of low water flow. Once fish accumulate near the back- current they are able to escape through a rigid framed opening in the net.

Figure 1: Sketch of the Popeye Fishbox BRD. Source QDPI.

The aim of this project was to trial the Popeye Fishbox BRD under the protocols of the NPF Bycatch Subcommittee performance assessment conditions in order to gain approval for usage in the NPF. The BRD was tested opportunistically at two different locations within the BRD to access potential changes in BRD performance. The BRD was also assessed for catch rates for all sharks, rays and Threatened Endangered and Protected (TEP) species.

Methods

At sea testing of the Popeye Fishbox BRD was conducted onboard the FV Adelaide Pearl during the last three weeks of the 2006 NPF tiger prawn season (24 October to 15 November 2006). The trial was conducted during normal commercial operations for 21 consecutive nights with an average of 4 shots per night for a total of 82 shots observed during the trial. The majority of sampling was conducted in the north- western area of the Gulf of Carpentaria, generally in the region north of Groote Eylandt.

2 The performance of the the Popeye Fishbox BRD was assessed using the NPF Bycatch Subcommittee’s performance requirements. These requirements quantify the effectiveness of the BRD by comparing a net containing a BRD to a net lacking a BRD. Using the presence or absence of a BRD in the paired nets as the sole controlled variable, we can then assume that differences in bycatch between nets reflect the impact of the BRD. For this purpose paired nets were assessed simultaneously with both nets retaining Turtle Excluder Devices (TEDs) to ensure the study replicated normal commercial conditions. Bycatch and prawns from each net were separated by a dividing panel placed in the hopper allowing each net to be processed independently.

The BRD was tested at two different positions during the trial; firstly with the BRD located 70 meshes from the codend drawstring (Fig. 2a) and secondly at 100 meshes from the codend drawstring (Fig. 2b). The first trial was conducted for a two week period while targeting tiger prawns and completing 54 shots as recommended by the protocols of the NPF Bycatch Subcommittee performance assessment. The second trial at 100 meshes was conducted opportunistically over a shorter period of 1 week, also targeting tiger prawns, and completing 30 shots. The BRD was swapped between port and starboard side nets once during each trial. Data for the two positions trialed were analysed separately for the purposes of this study. In addition six shots during the trial targeted banana prawns. As the study was intended to analyse the BRD performance during normal tiger prawn operations, data from these shots were treated separately due to the large volumes of catch experienced during banana prawn fishing biasing BRD performance.

Both starboard and port nets used a headrope length of 14.86 metres, footrope length of 16.60 metres, with the headrope pulled up two links per side and the ground chains pulled up three links per side. Both nets had size eight Bison Boards and a drop chain height of 7 links. Trawl netting meshes were 2.5 inches (57 mm). The distance of BRD from the codend drawstrings during the 70 meshes was 3.99 metres and 5.70 metres during the 100 meshes trial.

Shots that were suspected of being TEDed1, or had obvious tears were excluded from the assessment. Comparison of tiger prawn catches between nets was used as a measure of the possibility of a TEDing. If one net was substantially down in tiger prawn weight then this could represent a large animals (e.g. rays or sponges) having become stuck in the TED opening, leaving the flap ajar, and hence experiencing prawn and bycatch loss. This is a reliable measure of a TEDing as each trawl involves numerous runs over the same ground during a shot, consequently the randomness of spatial and temporal catch distribution should become relatively even between the nets over the period of the shot.

All bycatch was weighed in lug baskets to the nearest kilogram with a 50kg spring scale. All sharks, rays and seasnakes were separated from the bycatch for identification and counting, with all shark species collectively weighed for each shot. Seasnakes were either measured onboard or photographed with a calibration scale for further measurement and identification. Prawn catch for each net was weighed separately by the crew to the nearest kilogram. Species composition of small bycatch was assessed from a random subsample of each net obtained by shovel until

1 A ‘TEDing’ refers to when a large organism, typically a ray, shark or turtle, becomes wedged in either the TED or the escape flap through which the TED directs these organisms. Under these circumstances the large organism can substantially block the flow of catch into the codend and redirect it through the escape flap resulting in significant loses of both catch and bycatch. A TEDing is identified by an unusually large difference in the volume between the two codends that can not be explained by other factors.

3 reaching a weight of 10 kg from bycatch spilt onto the hopper trays before being processed into the hopper. All species from subsamples were counted and photographed for further identification.

Figure 2 a,b: Position of the Popeye Fishbox BRD during the trial. Source QDPI.

Comparisons of prawn and bycatch data for the four nightly shots were carried out using three-way factorial ANOVA contained in the STATISTICA™ package. Each shot was classified as dusk, early night, late night and dawn. Dusk shots were generally performed between 6.30pm and 9.30pm; early evening shots between 9.30pm and 1.30am; late evening between 1.30am and 5.30am and dawn shots between 5.30am and 8.30am. Catch data were log10(n+1) transformed, following the results of the Cochran’s Test for the homogeneity of variance. The Tukey-Kramer procedure was used to ascertain which variables were significantly different from each other. A two-way t-test was utilised to ascertain whether prawn catch between nets with or without the BRD were significantly different.

Results

BRD located 70 meshes from codend drawstrings

A total of 54 shots were trialed with the BRD located at 70 meshes from the codend drawstrings with the data from an additional eight shots excluded from the assessment due to TEDing or operational errors. The amount of bycatch obtained per trawl during the trial ranged between 1,426 to 64 kg with a total of 30,654kg measured. The net containing no BRD accounted for 15,768 kg of bycatch with an average of 350.4 kg per shot whilst the net containing the Popeye Fishbox BRD

4 accounted of 7,563 kg of bycatch with an average of 168.1 kg per shot (Fig. 5, Table 1). This represented a reduction in the mean bycatch obtained in the Popeye Fishbox BRD of 48% (Table 1).

Prawn catch during the 70 meshes trial ranged between 138.2 kg and 3kg (Fig. 4). Average prawn catch for the net with no BRD was 36 kg whilst average prawn catch per shot for the Popeye Fishbox BRD was 35.3 kg representing a reduction of 1.9% (Fig. 6, Table 1). The difference in prawn catch between the net with no BRD and the net containing the Popeye Fishbox BRD was not found to be significantly different (P = >0.05).

1600

1400 Popeye Fishbox No BRD 1200

1000

800

600 Total bycatch (kg) bycatch Total

400

200

0 1 6 10 14 24 28 32 36 40 46 50 54 Shot Number

Figure 3: Total small bycatch (kg) by each trawl for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

5 200

180 Popeye's fishbox 160 No BRD

140

120

100

Total prawn catch (kg) catch prawn Total 60

0 1 6 10 14 24 28 32 36 40 46 50 54 Shot Number

Figure 4: Total prawn catch (kg) by each trawl for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

500

400

300

200 350.4 100

Mean bycatch (kg) 168.1 0 Popeye's fishbox No BRD

Figure 5: Mean total bycatch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

6 50

20 35.3 36.0

10 Mean catch prawn (kg) 0 Popeye's fishbox No BRD

Figure 6: Mean total prawn catch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

Table 1: Comparison of the Popeye Fishbox BRD bycatch and prawn catch during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

Total Mean Samples Standard Standard 95% Mean (kg) (kg) (n) distribution. error C.I. reduction % Fishbox bycatch 7563 168.1 45 112.2 16.7 33.7 -48.0

No BRD bycatch 15768 350.4 45 300.8 44.8 90.4

Fishbox prawn 1587 35.3 45 23.2 3.5 7.0 -1.9% catch No BRD prawn 1618 36.0 45 28.0 4.2 8.4 catch

Comparison of the four nightly shots was conducted during the 70 meshes trial. Each shot was classified as dusk, early night, late night and dawn. Dusk shots were generally performed between 6.30pm and 9.30pm; early evening shots between 9.30pm and 1.30am; late evening between 1.30am and 5.30am and dawn shots between 5.30am and 8.30am.

Dawn shots had the highest average amount of bycatch for the net containing no BRD (593.2 kg, S.E. 142.2) and the greatest reduction in bycatch between the net with no BRD and the Popeye Fishbox BRD (65.8 %) (Fig. 7). Late night shots had the lowest average amount of bycatch for the net containing no BRD (218.8 kg, S.E. 43.7) and the lowest reduction in bycatch between the net with no BRD and the Popeye Fishbox BRD (32.1 %) (Fig. 7). Average bycatch weights were found to be significantly lower for the Popeye Fishbox BRD during all shots (Table 2). For nets containing no BRD average bycatch weights were found to be significantly higher during dawn shots (Table 2).

The highest average prawn catches for nets with and without a BRD were obtained during early night shot (43.8 and 46.2 kg respectively) whilst the lowest average catch was obtained during dawn shots (17.3 and 15.5 kg) (Fig. 8). Differences in average prawn catch for nets with and without a BRD were not significantly different, irrespective of time although average prawn catch during dawn shots were significantly lower for nets with and without a BRD (Table. 3).

7 700 Popeye's 600 fishbox 500 No BRD 400 300 200

Mean bycatchMean (kg) 100 0 Dusk Early night Late night Daw n

Figure 7: Mean total bycatch catches (kg + 95% C.I.) for dusk, early night, late night and dawn hauls for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. Popeye's 60 fishbox 50 No BRD 40 30 20 10

Mean prawnMean catch (kg) 0 Dusk Early night Late night Daw n

Figure 8: Mean total prawn catch (kg + 95% C.I.) for dusk, early night, late night and dawn hauls for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

Table 2: Three way ANOVA of mean bycatch for the Popeye Fishbox BRD, No BRD and time of shot (dusk, early night, late night and dawn) during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. Factors which were found to be dissimilar from each other for the Tukey-Kramer procedure are underlined. 1 represents dusk; 2 early evening; 3 late evening and 4 early morning. Factor SS Degrees MS F p Tukey of freedom Popeye Fishbox BRD 10.772 1 10.772 22.214 0.000010 /No BRD Time 5.509 3 1.836 3.787 0.013359 1 2 3 4 Popeye Fishbox BRD 0.772 3 0.257 0.531 0.662523 /No BRD *Time Error 40.734 84 0.485

8 Table 3: Three way ANOVA of mean prawn catch for the Popeye Fishbox BRD, No BRD and time of shot (dusk, early night, late night and dawn) during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF. Factors which were found to be dissimilar from each other for the Tukey-Kramer procedure are underlined. 1 represents dusk; 2 early evening; 3 late evening and 4 early morning. Factor SS Degrees MS F p Tukey of freedom Popeye Fishbox BRD 0.090 1 0.090 0.0256 0.873325 /No BRD Time 82.854 3 27.618 7.8129 0.000119 1 2 3 4 Popeye Fishbox BRD 0.644 3 0.215 0.0608 0.980254 /No BRD *Time Error 289.863 82 3.535

Shark and rays during the 70 meshes trial

During the 70 meshes trial 737 sharks representing 9 species were captured (Table 4). Nets containing no BRD captured 459 individual sharks for a total of 428.9 kg whilst nets containing the Popeye Fishbox BRD captured 278 sharks for a total 247 kg. This represented a reduction of 39.4 % in the number of individuals and 42.4 % reduction in total weight of shark species captured for the Popeye Fishbox BRD (Table 4). The average weight of individual sharks captured was 1.1 kg (Appn. B).

The most common shark species captured were milk sharks, blacktip sharks and whitecheeked sharks with the Popeye Fishbox BRD achieving reductions in the capture of individuals of 25.5, 48.9 and 67.6 % respectively for these species (Fig. 9, Table 4). All individual shark specimens obtained during the trial were found dead once processed through the hopper system with the exception of gray carpet sharks of which 91 % of individuals obtained from nets with no BRD were alive and 100 % of those obtained from the Popeye Fishbox BRD were alive (Table 4).

During the 70 meshes trial 764 rays representing 6 species were captured (Table 5). Nets containing no BRD captured 468 individual rays whilst nets containing the Popeye Fishbox BRD captured 298 rays representing a reduction of 36.8 % in the number of individuals captured for the Popeye Fishbox BRD (Table 5). The most common rays captured were blackspotted whiprays and Australian butterfly rays with the Popeye Fishbox BRD achieving reductions in the capture of individuals of 35.6 and 39.2 %, respectively for these species (Fig. 10, Table 5). The proportion of individuals obtained alive between nets containing no BRD and the Popeye Fishbox BRD were similar for most species (11-19%) with the exception of White spotted guitar sharks of which none were captured alive in the net with no BRD whilst 40% were obtained alive in the Popeye Fishbox BRD (Table 5). The only sawfish species captured during the trial were narrow sawfish with 5 individuals captured in the net with no BRD and 3 in the Popeye Fishbox BRD (Table 5).

9 300 No BRD

250 Popeye's fishbox

200

150

100 Total count Total

k k k k ark ar head sh shar Shar k shar l shark er il ai M ktip sh -t iger shark ac awny ham T T Weasel shark pot Bl S Leopard itecheeked oped h W Species Scall

Figure 9: Total count of all 9 shark species captured for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

300 No BRD 250 Popeye's fishbox 200

150

Total count Total 100

0 Blackspotted Australian Guitar shark Narraw Eagle ray Shovelnose whipray butterfly ray saw fish ray

Species

Figure 10: Total count of all 6 ray species captured for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

10 Table 4: Comparison of shark catches for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

Common name Species names Count No Count Total Total % BRD % BRD % % BRD BRD weight no weight change change alive alive BRD (kg) BRD (kg) count weight no BRD BRD Milk shark Rhizoprionodon 247 184 179.5 97.8 -25.5% -45.5% 0% 0% acutus Blacktip shark Carcharhinus tilstoni 88 45 118.8 90.2 -48.9% -24.1% 0% 0% Whitecheeked Carcharhinus 65 22 63.6 20.1 -66.2% -68.4% 0% 0% shark dussumieri Grey carpet shark Chiloscyllium 37 12 41.8 14.9 -67.6% -64.4% 91% 100% punctatum Weasel shark Hemigaleus 13 10 9 7.9 -23.1% -12.2% 0% 0% microstoma Spot-tail shark Carcharhinus sorrah 3 0 2.3 0 NA NA 0% NA Scalloped Sphyrna lewini 3 5 10.2 16.1 66.7% 57.8% 0% 0% hamerhead

Tiger shark Galeocerdo curvier 2 0 2.6 0 NA NA 0% NA Leopard Shark Stegostoma fasciatum 1 0 1.1 0 NA NA 0% NA Totals 10 (species) 459 278 428.9 247 -39.4% -42.4%

11 Table 5: Comparison of ray catches for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

Common name Species names Count Count % BRD % alive % alive No BRD BRD reduction no BRD BRD count Blackspotted Himantura toshi 281 181 -35.6% 11% 19% whipray Australian butterfly Gymnura australis 158 96 -39.2% 17% 18% ray White spotted guitar Rhynchobatus 21 10 -52.4% 0% 42% shark australiae Narrow sawfish Anoxypristis 5 3 -40.0% 25% 33% cuspidata Eagle ray Aebatus spp. 2 2 0.0% 0% 0% Shovelnose ray Rhinobatos typus 1 4 75.0% 0% 0% Totals 6 (species) 468 296 -36.8%

Seasnakes

A total of 40 seasnakes representing 6 species were captured during the 70 meshes trial. The net containing no BRD captured 35 seasnakes whilst the net containing the Popeye Fishbox BRD captured 5, representing an 87.5% reduction in the capture of seasnakes for the Popeye Fishbox BRD (Table 6). The elegant seasnake was the most common species captured during the trial with 16 and 4 individuals captured in the net with no BRD and the Popeye Fishbox BRD, respectively (Fig. 11). None of the four elegant seasnakes captured in the net containing the Popeye Fishbox BRD were alive as they were all trapped in the meshes of the codend.

18 16 No BRD 14 12 Popeye's fishbox 10

Count 8 6 4 2 0 Hydrophis Astrotia Disteira Hydrophis Lapemis Aipysurus elagans stokesii major pacificus hardwickii eydouxii Species

Figure 11: Total count of all 6 seasnake species captured for the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

Table 6: Comparison of seasnake catches for nets containing the Popeye Fishbox BRD and no BRD during the 70 mesh trial (25 Oct- 9 Nov 2006) conducted in the NPF.

No BRD Common name Species Count Average % released length alive Elegant seasnake Hydrophis 16 124.8 43% elagans Green banded Lapemis 2198 50% seasnake hardwickii Olive headed Disteira major 4176.8 25% seasnake Pacific seasnake Hydrophis 4195.8 50% pacificus Spine tailed seasnake Aipysurus 176100% eydouxii Stokes seasnake Astrotia stokesii 8 121 87.50% Totals 6 (species) 35 Popeye Fishbox BRD Common name Species Count Average % released length alive Elegant seasnake Hydrophis 4111.8 0 elagans Stokes seasnake Astrotia stokesii 1 128 100% Totals 2 (species) 5

BRD located 100 meshes from codend drawstrings

A total of 28 shots were trialed with the BRD located at 100 meshes from the codend drawstrings with the data from 2 shots excluded from the assessment due to being TEDed or operational errors. The amount of bycatch obtained during the trial ranged between 891 and 54 kg with a total of 12,334 kg measured (Fig. 12). The net containing no BRD accounted for 7,202 kg of bycatch with an average of 276.9 kg per shot whilst the net containing the Popeye Fishbox BRD accounted of 5,132 kg of bycatch with an average of 197.4 kg per shot (Fig. 14). This represented a reduction in the mean bycatch obtained in the Popeye Fishbox BRD of 28.7% (Table 7).

The average weight of bycatch during the 70 meshes trial was higher for nets with no BRD compared to results during the 100 meshes trial (350.4 kg compared to 276.9 kg) whilst nets containing the Popeye Fishbox BRD had higher levels of bycatch during the 100 meshes trial (168.1kg compared to 197.4 kg) (Figs. 3 and 11).

Prawn catch during the 100 meshes trial ranged between 335 kg and 11kg (Fig. 13). Average prawn catch for the net with no BRD was 58.9 kg whilst mean prawn catch per shot for the Popeye Fishbox BRD was 60.3 kg representing an increase of prawn catch of 3.1% (Fig. 15, Table 7). The difference in prawn catch between the net with no BRD

13 and the net containing the Popeye Fishbox BRD was not found to be significant (P = >0.05).

1000 No BRD

800 Fishbox

600

400 Bycatch (kg)

200

0 55 56 57 58 59 60 61 62 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82

Shot Number

Figure 12: Total small bycatch (kg) by each trawl for nets containing the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.

400 No BRD 300 Fishbox

200

Prawn catch (kg) 100

0 55 56 57 58 59 60 61 62 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 Shot number

Figure 13: Total prawn catch (kg) by each trawl for nets containing the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.

14 400

300

200

100 276.9 197.4 Mean bycatchMean (kg)

0 No BRD Fishbox

Figure 14: Mean total bycatch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.

40 58.9 60.3 20 Mean prawn catch (kg) 0 No BRD Fishbox

Figure 15: Mean total prawn catch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.

Table 7: Comparison of the Popeye Fishbox BRD bycatch and prawn catch during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.

Total Mean Samples Standard Standard 95% Mean (kg) (kg) (n) distribution error C.I. change % Fishbox bycatch 5132 197.4 26 116.5 22.8 46.9 -28.7% No BRD bycatch 7202 276.9 26 190.6 37.4 76.8 Fishbox prawn 1567 60.3 26 67.3 13.2 27.1 +3.1% catch No BRD prawn 1532 58.4 26 66.4 13.0 26.8 catch

Sharks and rays during 100 meshes trial

During the 100 meshes trial 476 sharks representing 7 species were captured (Table 8). Nets containing no BRD captured 264 individual sharks for a total of 220.8 kg whilst nets containing the Popeye Fishbox BRD captured 212 sharks for a total 136 kg. This represented a reduction of 19.7 % in the number of individuals and 38.4% reduction in total weight of shark species captured for the Popeye Fishbox BRD (Table 8). The average weight of individual sharks captured was 1.3 kg (Appn. B).

The most common shark species captured were milk sharks, blacktip sharks and whitecheeked sharks with the Popeye Fishbox BRD achieving reductions in the capture of individuals of 16.3, 44.4 and 27.3 % respectively, for these species (Fig. 16, Table 8). All individual shark specimens caught during the trial were found dead once processed through the hopper system with the exception of weasel sharks of which 89% of individuals obtained from nets with no BRD were alive and 88% of those obtained from the Popeye Fishbox BRD were alive (Table 8).

385 rays representing 7 species were captured during the 100 meshes trial (Table 9). Nets containing no BRD captured 234 individual rays whilst nets containing the Popeye Fishbox BRD captured 151 rays representing a reduction of 35.1 % in the number of individuals specimens captured for the Popeye Fishbox BRD (Table 9). The most common rays captured were blackspotted whiprays and Australian butterfly rays with the Popeye Fishbox BRD achieving reductions in the capture of individuals of 33.9 and 35.4% respectively for these species (Fig. 17, Table 8). The proportion of individuals obtained alive between nets containing no BRD and the Popeye Fishbox BRD were similar for most species with the exception of white spotted guitar sharks of which 33% were captured alive in the net with no BRD whilst 88% were obtained alive in the Popeye Fishbox BRD (Table 8). The only sawfish species captured during the trial was narrow sawfish with one individual captured in the net with no BRD (Table 8).

16 200 No BRD Popeye's fishbox

150

100 Total count

0 Milk shark Blacktip Whitecheeked Tawny shark Weasel shark Scalloped Spinner Shark shark shark hamerhead Species

Figure 16: Total count of all 7 shark species captured for the Popeye Fishbox BRD and no BRD during the 100 meshes trial (25 Oct- 9 Nov 2006) conducted in the NPF.

180 160 No BRD 140 Popeye's fishbox 120 100 80

Total count 60 40 20 0 Black Australian Guitar Eagle ray Blue Narrow Reticulate spotted ray butterfly shark Spotted saw fish whipray ray Ray

Figure 17: Total count of all 7 ray species captured for the Popeye Fishbox BRD and no BRD during the 100 meshes trial (25 Oct- 9 Nov 2006) conducted in the NPF.

17 Table 8: Comparison of shark catches for nets containing the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF. Common Species names Count Count Total Total % BRD change % BRD % Alive no % Alive name No BRD weight weight count change BRD BRD BRD no BRD BRD weight (kg) (kg) Milk shark Rhizoprionodon acutus 190 159 109.1 77.9 -16.3% -28.6% 0% NA Blacktip shark Carcharhinus tilstoni 9 5 20.8 12.5 -44.4% -39.9% 0% NA Whitecheeked Carcharhinus 44 32 64.2 30.4 -27.3% -52.6% 0% 3% shark dussumieri Grey carpet Chiloscyllium 12 14 9.1 13.3 16.7% 90.0% 0% 0% shark punctatum Weasel shark Hemigaleus 1 2 0.9 1.9 50.0% -52.6% 89% 88% microstoma Scalloped Sphyrna lewini 7 0 14.4 0 -100.0% -100.0% 0% 0% hamerhead Spinner Shark Carcharhinus 1 0 2.3 0 NA NA 0% 0% brevipinna Totals 10 (species) 264 212 220.8 136 -19.7% -38.4%

Table 9: Comparison of ray catches for nets containing the Popeye Fishbox BRD and no BRD during the 100 mesh trial (9-16 Nov 2006) conducted in the NPF.

Common name Species names Count No BRD Count BRD % BRD % alive no % alive change count BRD BRD Australian butterfly ray Gymnura australis 56 37 -33.9% 3% 0% Black spotted ray Himantura toshi 164 106 -35.4% 0% 0% Blue Spotted Ray Dasyatis kuhlii 2 0 -100.0% 50% NA Eagle ray Aetobatus narinari 4 1 -75.0% 0% 0% Guitar shark Rhynchobatus australiae 6 7 14.3% 33% 88% Narrow sawfish Anoxypristis spp. 1 0 -100.0% 100% 0% Reticulate whipray Himantura uarnak 1 0 -100.0% 0% NA Totals 7 (species) 234 151 -35.5%

18 Banana prawn catches

Banana prawn schools were targeted in 6 shots during the trial. Mean bycatch per shot for the net with no BRD was 556.5 kg whilst mean bycatch per shot for the Popeye Fishbox BRD was 263.2 kg representing a reduction of 52.7% (Fig. 18, Table 10). Mean prawn catch for the net with no BRD was 135.3 kg whilst mean prawn catch per shot for the Popeye Fishbox BRD was 112 kg representing a reduction of 17.2% (Fig. 19, Table 10).

800

600 h kg) ( h kg)

400 b

ean ycatc 200 M

0 No BRD Popeye's fishbox

Figure 18: Mean total bycatch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD whilst targeting banana prawns (9-16 Nov 2006).

200

150

100

50 Mean prawnMean catch (kg) 0 No BRD Popeye's fishbox

Figure 19: Mean total prawn catch (kg + 95% C.I.) for the Popeye Fishbox BRD and no BRD whilst targeting banana prawns (9-16 Nov 2006).

19 Table 10: Comparison of the Popeye Fishbox BRD bycatch and prawn catch whilst targeting banana prawns during the BRD trial (24 Oct-16 Nov 2006) conducted in the NPF.

Total (kg) Mean Samples S.D. S.E. 95% Mean (kg) (n) C.I. reduction % Fishbox bycatch 1579 263.2 6 74.6 30.4 74.5 -52.7% No BRD bycatch 3339 556.5 6 347.2 141.7 346.8 Fishbox prawn 672 112.0 6 27.1 11.1 27.1 -17.2% catch No BRD prawn 812 135.3 6 38.7 15.8 38.7 catch

Catch composition

Small bycatch composition was analysed for 4 shots during the trial. Fish species were categorised into three habitant preference groups namely demersal, pelagic and other (Table 11). The proportional composition of these groups for nets containing the Popeye Fishbox BRD was dominated by demersal species (57%) whilst demersal species accounted for 32% of the composition of nets without a BRD (Fig. 20, Table 11). The net without a BRD was dominated by pelagic species (51%) whilst pelagic species in the net containing the Popeye Fishbox BRD accounted for 20% of the composition (Fig.20, Table 11).

Popeye's fishbox No BRD

17% 23% 32% Demersal Pelagic 57% Other 20%

51%

Figure 20: Proportion of demersal, pelagic and other fish species for nets containing the Popeye Fishbox BRD and no BRD obtained from subsamples during the BRD trial (24 Oct-16 Nov 2006) conducted in the NPF.

20 Table 11. Counts of small bycatch species/taxa from subsamples of shots 8, 14, 26 and 52 BRD trial (24 Oct-16 Nov 2006) conducted in the NPF. D = Demersal fish taxa; P = Pelagic/semi-pelagic fish taxa, O = Other or unclassifiable fish taxa. Shot 8 Shot 14 Shot 26 Shot 52 Totals Family Species/taxa Common name BRD No BRD No BRD No BRD No BRD No Category BRD BRD BRD BRD BRD Acropomatidae Synagrops phillippinensis Sharptooth seabass 0 1 0 0 1 0 0 0 1 1 O Apogonidae Apogon albimaculosus Creamspotted cardinalfish 0 0 1 0 0 0 0 0 1 0 O Apogonidae Apogon poecilopterus Pearlyfin cardinalfish 0 0 0 1 0 0 1 0 1 1 O Arridae Arius nella Shieldhead catfish 0 1 2 1 2 0 2 1 6 3 D Bregmacerotidae Bregmaceros mcclellandi Unicorn codlet 2 0 1 2 2 0 2 1 7 3 O Carangidae Alectis indica Diamond trevally 0 0 0 0 0 1 0 1 0 2 P Carangoides malabaricus Malabar trevally 0 0 2 3 0 3 0 3 2 9 P Caranx ignobilis Giant trevally 0 2 0 2 0 4 1 6 1 14 P Megalaspis cordyla Finny scad 0 0 0 1 0 1 0 0 0 2 O Parastromateus niger Black pomfret 1 0 1 0 1 0 0 1 3 1 P Centrolophidae Psenopsis humerosa Blackspot butterfish 1 2 0 0 1 0 0 2 2 P Cynoglossidae Cynoglossid sp. Tongue soles 2 1 1 0 3 0 5 1 11 2 D Diodontidae Diodontid sp. Porcupinefishes 1 0 1 0 1 0 1 4 0 D Engraulidae Engraulid sp. Anchovy species 1 3 1 4 1 2 1 2 4 11 P Setipinna tenuifilis Hairfin anchovy 0 0 0 0 0 1 0 0 0 1 P Ephippidae Rhinoprenes pentanemus Threadfin scat 0 0 1 0 1 0 1 0 3 0 O Zabidius novemaculeatus Shortfin batfish 0 1 0 1 1 0 0 2 1 4 P Fistulariidae Fistularia commersonii Smooth flutemouth 2 3 0 1 0 0 2 2 4 6 O Haemulidae Pomadasys maculatus Blotched Javelin 0 0 0 0 1 0 0 0 1 0 O Leiognathidae Leiognathid sp. Dollarfishes 2 7 12 21 3 8 2 15 19 51 P Lutjanidae Lutjanid sp . Unidendentified Lutjanids 0 3 1 0 0 0 0 0 1 3 O Lutjanus bohar Red bass 1 1 0 0 0 0 0 0 1 1 O Lutjanus russelli Moses perch 0 0 0 2 0 0 0 1 0 3 O Lutjanus sebae Red emperor 0 0 0 0 0 1 0 0 0 1 O Monacanthidae Monacanthid spp Leatherjackets 3 1 1 0 2 0 1 1 7 2 D Mugulidae Mugulid sp. Mullets 0 0 0 0 0 1 0 0 0 1 O Mullidae Upeneus sulphureus Sunrise goatfish 2 4 3 2 1 2 3 1 9 9 O Nemipteridae Nemipterus hexodon Ornate threadfin bream 0 0 0 0 0 2 0 0 0 2 O Ophidiidae Sirembo imberbis Golden cusk 0 2 2 1 1 1 2 1 5 5 D Opistognathidae Opistognathus inornatus Jawfish 0 0 1 0 2 0 1 0 4 0 D Paralichthyidae Paralichthyid sp. Sand flounders 1 0 0 0 3 0 4 0 8 0 D Platycephalidae Cociella hutchinsi Brownmargin flathead 1 1 1 0 2 0 1 0 5 1 D Inegocia harrisii Harris' flathead 0 0 1 0 1 0 1 0 3 0 D

Table 8. Continued

Shot 8 Shot 14 Shot 26 Shot 52 Totals Family Species Common name BRD No BRD No BRD No BRD No BRD No Category BRD BRD BRD BRD BRD Pleuronectidae Psettodes erumei Queensland halibut 3 4 1 1 2 1 2 0 8 6 D Plotosidae Euristhmus nudiceps Nakedhead catfish 0 2 0 1 0 0 3 1 3 4 D Polynemidae Polynemid sp. Threadfin salmons 0 1 0 1 0 1 1 0 1 3 O Pristigasteridae Pellona ditchela Ditchelee 0 0 0 0 1 0 0 0 1 0 O Sciaenidae Atrobucca brevis Orange jewfish 1 0 0 1 0 0 1 0 2 1 O Johnius borneensis River jewfish 0 0 0 0 0 1 0 0 0 1 O Johnius laevis Smooth jewfish 3 0 0 0 1 0 0 0 4 0 O Scombridae Scomberomorus Spanish mackerel 0 0 1 2 0 1 0 3 1 6 P commersoni Scomberomorus munroi Spotted mackerel 0 1 0 4 0 2 0 1 0 8 P Serranidae Epinephelus sexfasciatus Sixbar grouper 0 0 0 1 0 0 0 1 0 2 O Serranid sp. Unidendentified grouper 0 0 1 0 0 0 0 0 1 0 O Sphyaenidae Sphyraena obtusata Striped barracuda 0 0 0 1 0 0 0 1 0 2 P Sphyraena putnamae Sawtooth barracuda 0 0 0 0 0 1 0 0 0 1 P Synodontidaer Synodus sp. Sauries 2 4 2 8 2 6 3 8 9 26 D Terapontidae Terapon theraps Largescale grunter 0 0 0 0 1 0 0 0 1 0 O Tetraodontidae Tetraodontid sp. Toadfishes 1 0 2 0 1 0 0 3 4 3 D Triacanthidae Trixiphichthys weberi Blacktip tripodfish 2 1 3 1 2 4 1 4 8 10 D Trichiuridae Trichiurus lepturus Largehead hairtail 1 0 0 2 1 2 0 0 2 4 P Triglidae Lepidotrigla russelli Smooth gunard 2 1 1 2 1 0 1 1 5 4 D

Portunidae Charybdis callianassa Cornflake crab 1 0 0 1 2 1 1 0 4 2 Portunidae Charybdis truncata Blunt-toothed crab 2 0 0 1 0 0 2 1 4 Portunidae Portunus sanguinolentus Three-spotted crab 1 0 2 0 0 2 0 1 3 3 Portunidae Portunid sp. Unidendified swimming 01 10200031 crabs

Squillidae Squillid sp. Mantis shrimps 2 3 1 4 1 2 1 4 5 13

Enoploteuthidae Enoploteuthid sp. Squids 1 3 0 0 1 2 1 1 3 6

Scyllaridae Scyllarid sp. Bugs 0 1 0 0 1 0 1 0 2 1 185 252

22 Discussion

The Popeye Fishbox BRD, having achieved a reduction in small bycatch of 48% when located at 70 meshes from the codend, has achieved the best results to date for BRDs trialed in the NPF. This result equates to a reduction of 8,205 kg in the amount of small bycatch excluded during the 14 day trial. If the same results were achieved throughout the entire tiger prawn season (106 days) on the same vessel approximately 62,000 kg of bycatch would be excluded. Extending this equation to the entire fleet (82 vessels during 2006) would achieve and approximate reduction in the amount of small bycatch of 5,084,000 kg.

In addition to the excellent small bycatch results the Popeye Fishbox BRD also achieved an 87.5% reduction in the number of seasnakes captured and a 38.1% reduction in the number of small sharks and rays captured. This combined with no significant change in prawn catch makes the implementation of the Popeye Fishbox BRD in the NPF highly desirable. The use of the Popeye Fishbox BRD would greatly enhance the Fishery’s ability to meet the Ministerial Direction on halving bycatch whilst having minimal economic and operational impacts.

Opportunistic testing of the BRD at a distance further from the codend drawstrings during this trial (100 meshes) suggests that the location of the Popeye Fishbox BRD may be an important factor in achieving improved bycatch reduction. The reduced bycatch exclusion results during the 100 meshes trial may have been more prone to being affected by changes in environmental conditions or other operational issues due to the smaller sampling number. The bycatch reduction figures during this trial at 100 meshes were similar to those achieved during trials by QDPI conducted in north-eastern Queensland (tested at 90 meshes and achieving a 30% reduction). This would suggest that results achieved during this trial were not adversely affected by the reduced sampling period.

A 17% reduction in prawn catch whilst targeting banana prawns during the trial suggests the Popeye Fishbox BRD may not be suitable for usage during the banana prawn season. The author and crew members observed prawns and bycatch escaping from the BRD whilst nets were being retrieved. This was most likely due to nets filling past the location of the BRD and a backflow of water forcing catch through the BRD. Further research and possible testing for a device to prevent a backflow of prawns through the BRD whilst hauling to reduce escapement is recommended.

Analyses of bycatch and prawn catch by time of shot were also undertaken during the trial. These analyses showed that morning shots (generally between 5.30 and 8.30am) had approximately twice the amount of bycatch and half the prawn catch for nets without a BRD. It is assumed that this was due to the migration of fish from mid-water to the seafloor during the early morning making them more susceptible to capture in trawl nets. Restricting prawn trawling to hours before sunrise (5.30-6.00am) may also achieve large reductions in the amount of bycatch. As prawn catch during morning shots was significantly lower, this may be beneficial to industry via savings in fuel and crew effort. In order to compensate industry for the reduced time available for fishing, season dates could be extended.

Analyses of catch composition of small bycatch was only conducted on four shots during the trial. Despite the limitations of this data, it was found that the catch composition of small bycatch obtained in the Popeye Fishbox BRD had a higher proportion of demersal categorised fish species. This may be due to the poor swimming ability of demersal fish species preventing their

23 ability to swim at speeds faster than the trawl nets and therefore being unable to escape via the BRD. It may also be due to the behavioral response of these species when encountering trawl gear with some species tending to swim upwards in flight response, while others may swim laterally. Further research on the catch composition of the Popeye Fishbox BRD may benefit future design and positioning of the BRD.

Conclusions/Recommendations

From the performance of the Popeye Fishbox BRD during the observer trials, the author would encourage the NPF Bycatch Subcommittee to recommend that NORMAC include the Popeye Fishbox BRD as an approved BRD design.

Opportunistic testing of the BRD at a distance further from the codend drawstrings during this trial (100 meshes) suggests that the location of the Popeye Fishbox BRD is an important factor in achieving improved bycatch reduction.

It is recommended that funding for additional research be sought by AFMA and industry. Further trials of the BRD to improve and analyse performance include:

o Testing at the Australian Maritime College Flume facilities to analyse and possibly improve water flow dynamics that may attract unwanted catch towards the BRD exit. o Further at sea trials investigating BRD performance at different distances from the codend drawstings. o Trials of backflow devices to prevent prawn escapement during large catches such as those encountered during the banana prawn season.

24 References

Alverson, D.L., Freeberg, M.H., Murawksi, S. A. and Pope, J.G. (1994) A global assessment of fisheries bycatch and discards. FAO Fisheries Technical Paper. 339, 1-233.

Barratt, D., Garvey, J. and Chesson, J. (2001) Marine Disturbance in Parts of the Australian Exclusive Economic Zone. In: Australia: State of the Environment Second Technical Paper Series (Coasts and Oceans), Series 2. Department of the Environment and Heritage, 2001.

Brewer, David, Don Heales, David Milton, Quinton Dell, Gary Fry, Bill Venables and Peter Jones. 2006. The impact of Turtle Excluder Devices and Bycatch Reduction Devices on diverse tropical marine communities in Australia’s Northern Prawn Trawl Fishery. Fisheries Research 81, 176-188

Day, G. (2000). At-sea testing and assessment of the John Thomas Bigeye Turtle Excluder Device as an approved TED for Australia’s Northern Prawn Fishery. Fishing Technology Unit, Australian Maritime College, Tasmania.

Hall, S.J. and Mainprize, B.M. (2005). Managing by-catch and discards: how much progress are we making and how we can do better. Fish and Fisheries. 6, 134-155.

Stobutzki, I., Balber, S., Brewer, D., Fry, G., Heales, D., Miller, D., Miller, M., Milton, D., Salini, J., Van der Velde, T., Wassenberg, T., Jones, P., Wang, Y., Dredge, M., Courtney, T., Chilcott, K., and Eayrs, S. (2001a). Ecological sustainability of bycatch and biodiversity in prawn trawl fisheries. FRDC Project 96/257.

Stobutzki, I.C., Miller, M.J and Brewer, D.T.(2001b). Sustainability of fishery bycatch: a process for assessing highly diverse and numerous bycatch. Environmental Conservation. 28, 167-181.

Stobutzki, I.C., Miller, M.J., Heales, D. S. and Brewer, D.T. (2002) Sustainability of elasmobranches caught as bycatch in a tropical prawn (shrimp) trawl fishery. Fisheries Bulletin. 100, 800-821.